Prostates protected by vitamin D: study

The benefits of vitamin D for prostates may be due to the action of
the vitamin on a specific gene, suggests new research that deepens
our understanding of how nutrients and genes interact.

Researchers from the University of Rochester Medical Center report
that the active form of vitamin D in the body, 1,25-hydroxylvitamin
D3 (1,25(OH)2D), may link with a gene known as G6PD, which releases
an antioxidant enzyme and protect DNA from damage.
"Many epidemiological studies have suggested the beneficial
properties of vitamin D,"​ said lead researcher Yi-Fen Lee.
"Our findings reflect what we see in those studies and
demonstrate that vitamin D not only can be used as a therapy for
prostate cancer, it can prevent prostate cancer from
happening."​
The study is published in the International Journal of
Cancer​.
The link between vitamin D intake and protection from cancer dates
from the 1940s when Frank Apperly demonstrated a link between
latitude and deaths from cancer, and suggested that sunlight gave
"a relative cancer immunity."​
Vitamin D refers to two biologically inactive precursors - D3, also
known as cholecalciferol, and D2, also known as ergocalciferol.
Both D3 and D2 precursors are hydroxylated in the liver and kidneys
to form 25- hydroxyvitamin D (25(OH)D), the non-active 'storage'
form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically
active form that is tightly controlled by the body.
There is growing evidence that 1,25(OH)2D has anticancer effects,
but the discovery that non-kidney cells can also hydroxylate
25(OH)D had profound implications, implying that higher 25(OH)D
levels could protect against cancer in the local sites.
The new study, supported by a grant from the U.S. Department of
Defense, appears to provide further compelling evidence of the
potent anti-cancer benefits of 1,25(OH)2D.
Normal healthy prostate cells (BPH-1 and RWPE-1) and prostate
cancer cells (CWR22R and DU 145) were subjected to oxidative
stress. The researchers found that 1,25(OH)2D induced G6PD
(glucose-6-phosphate dehydrogenase), a key antioxidant enzyme, in
the healthy but not cancer cells. G6PD scavenges reactive oxygen
species (ROS) associated with DNA damage.
"If you reduce DNA damage, you reduce the risk of cancer or
aging,"​ said Lee said. "Our study adds one more beneficial
effect of taking a vitamin D supplement. Taking a supplement is
especially important for senior citizens and others who might have
less circulation of vitamin D, and for people who live and work
areas where there is less sunshine."​
"In this study, we have demonstrated that 1,25-(OH)2D can
protect nonmalignant human prostate epithelial cells against
H2O2-induced cell death through modulating the ROS defense systems,
suggesting a possible role of 1,25-(OH)2D in prostate cancer
prevention,"​ stated the researchers in the journal.
Vitamin D - bad for cancers, good for
you ​
Lee and co-workers noted that 1,25(OH)2D may act both as an
antioxidant and a pro-oxidant, depending on the cellular
environment, with a subtle pro-oxidant activity found in cancer
cells, while it appears to behave as an antioxidant in normal
healthy cells.
"[Our] data suggest that vitamin D might exert a subtle
oxidative stress, which could stimulate the detoxification
mechanisms to protect cells from the subsequent stress challenges;
yet cancer cells lose the 1,25-(OH)2D-induced detoxification
responses, therefore, 1,25-(OH)2D acts as a pro-oxidant in cancer
cells,"​ they said.
"Our results provide one mechanism to explain how 1,25-(OH)2D
protects nonmalignant human prostate epithelial cells from
oxidative stress to attenuate the accumulation of oxidative damages
during the life. ​ ​"Therefore, vitamin
D might be beneficial for preventing the development of
age-dependent diseases,"​ they concluded.
Source: The International Journal of Cancer​
122, 2699-2706 (2008)
"Protective role of 1a, 25-dihydroxyvitamin D3 against
oxidative stress in nonmalignant human prostate epithelial
cells" ​Authors: B.-Y. Bao, H.-J. Ting, J.-W. Hsu, Y.-F.
Lee